Printing telegraph apparatus



C. A. LEVlN 4 PRINTING TELEGRAPH APPARATUS Filed April 25, 1958 2 Sheets-Sheet 1 m V E L A. L R A C Cttorneg y Feb. 4, 1941.

Feb. 4, 1941. c. A. L r-:vlN

PRINTING 'TELEGBAPH APPARATUS Filed April 25, 1938 2 Sheets-Sheet 2 INVENTOR.

CARL' A. LEvlN A ORNEY.

Patented Feb. 4, 1941 TENT OFFICE PRINTING TELEGRAPH APPARATUS Carl A. Levin, Chicago, Ill., assigner to Teletype Corporation, Chicago, Ill., a corporation of Delaware Application Apm 25, 193s, serial No. 204,038

9 Claims.

This invention relates to printing telegraph apparatus and particularly to printing telegraph apparatus in which the characters are printed in page form from type elements carried upon the periphery of a rotatable and selectively arrestable type wheel.

An object of the invention resides in the provision, in a printing telegraph receiving unit embodying a type wheel having displaceable type elements, of instrumentalities for actuating said elements capable of extremely rapid positive operation.

Another object of the invention resides in the provision, in a keyboard controlled signalling mechanism, of instrumentalties for causing a mechanical function to accompany the operation of certain signalling keyboard members.

Another object of the invention resides in the provision of a simplified, easily assembled type wheel of the kind having displaceable type ele ments.

The invention features apparatus for actuating the individual type elements of a type wheel including a print hammer which is actuated by a cam follower and having a yieldable element included in the linkage interposed between the print cam and the print hammer whereby the actual printing operation is performed by the expenditure of kinetic energy of the print hammer and possibly an additional element or elements, such kinetic energy resulting m overtravel of the print hammer permitted by the yieldable element.

The invention also features a keyboard mechanism in which a mechanical condition that is set up in a printing telegraph receiving unit as the result of the generation of a particular signal combination either locally or distantly is abolished by a mechanical action resulting from the operation of the key lever which, upon being operated, causes the generation of a signal combination which, while being entirely unrelated to the signal combination which established the mechanical condition, is particularly suited to be in process of generation at the time of abolition of mechanical condition.

In a copending application Serial No. 77,796, filed May 4, 1936, by Albert H. Reiber, there is disclosed a type wheel printer with reference to which the present invention stands as an improvement. According to the disclosure of that application the displaceable type elements carried by the type wheel are individually actuated by a pivoted actuating member which is operated by a pivotally mounted impact member or hammer. Operation of the hammer through a full stroke sufficient to cause the printing of a character is effected by a cam operated bail.

According to the present invention a reciprocable printing member is provided for actuating the type elements individually. A bail carries a follower roller which engages the periphery of a printing cam, the bail being biased into engagement with the cam by a tension spring. Operation of the printing member is effected when the printing bail cam follower roller rides down an abrupt drop in the. printing cam. The distance through which the printing bail is operated by its spring is insunicient to bring the printing member into engagement with a type element. A spring is interposed between the printing bail and the printing member, and inertia of the element to which motion is imparted by the printing bail causes those elements to overtravel, the interposed `spring yielding and permitting the overtravel, and the amount of overtravel is suiiicient to cause a selected type element to effect printing. The spring which yields and permits the overtravel immediately retracts the printing element to unoperated position, thereby clearing the path of unoperated type elements so that the type wheel may be rotated to a new position.

A type wheel disclosed in copending application Serial No. 77,796 and also in a copending application Serial No. 77,794, filed May 4, 1936, by Howard L. Krum et al., comprises spaced slotted anges joined by a cylindrical drum portion which is also slotted. Type pallets slidable radially of the type wheel are mounted in the slots in the type wheel, there being two type pallets in each slot. The Shanks of the type pallet in the upper row have recesses which open downwardly, and the shanks of the type pallets in the lower row have recesses which open upwardly. A garter spring individual to each row of type pallets is disposed in the recesses in the Shanks of all of the type pallets in a row and biases the pallets to their innermost positions. A iioating ring partially enters the space between the two garter springs, whereby it rests upon and is supported by one of the springs and whereby it also prevents the springs from shifting out of the desired position.

In the type wheel according to the present invention the drum portion of the Wheel which joins the upper and lower flanges has a peripheral rib intermediate the upper and lower flanges. The rib thus divides the surface of the drum portion into two peripheral grooves which serve as seats for the garter spring and confine the springs in the desired position. 4The garter springs are thus kept in proper position without the assistance of a floating ring.

The copending application Serial No. 77,796 disclosed signal responsive function mechanism for closing a pair of contacts which establish a short circuit across the transmitting contacts of the keyboard transmitter mechanism so that the telegraph line to which the transmitter and receiving unit are connected will not be aiected should any of the signal transmitting key levers be operated, the purpose of the contacts being to disable the transmitter and to place the apparatus in a receiving only condition. The function lever which closes the contacts becomes latched to hold the contacts closed. The present invention contemplates the provision of a contact unlatching attachment for the key lever of the keyboard transmitter mechanism which initiates a letters or unshiit signal combination. Thus, when the unshift key lever is operated, the permutation code mechanism is set for the trans` mission of the unshift signal combination, the transmitting distributor is released for operation, and the latch which is holding the short circuit across the transmitting contacts is disabled so that the short circuit is broken. The unshift or letters key lever is peculiarly adapted to perform the unlatching of the short circuiting contact for the reason that the letters or unshiit signal combination, according to a generally used permutation code system, is the all-marking combination, in which all of the code impulses are of marking nature. Thus, the short circuiting contacts may be permitted to open at any time during the cycle of rotation of the transmitting cam shaft without the line actually becoming opened, the transmitting contacts maintaining the line in closed condition. Since the transmitting'contacts impose a continuous marking condition upon the line during the rotation of the transmitting cams, the opening of the short circuiting contacts cannot introduce a spacing condition and therefore the receiving distributors of receiving units connected to the line will not be released for an idle or unwanted receiving operation.

Certain features of invention disclosed but not claimed herein are also disclosed and are claimed in copending applications Serial No. 193,642 i'lled March 3, 1938 by Albert H. Reiber, Serial No. 203,021, led Apr. 20, 1938, by Berthel F. Madsen, Serial No. 208,761, iled May 19, 1938. by Edward S. Larson, Serial No. 210,816, filed May 31, 1938, by Carl W. Swan, and Serial No. 211,496, filed June 3, 1938, by Herman Lotterman.

For a complete understanding of the invention, reference may be had to the following detailed description to be interpreted in the light of the accompanying drawings, wherein Fig. 1 is a perspective view of the combined transmitting and receiving mechanism according to the present invention, certain portions being broken away to clarify the showing;

Fig. 2 is a plan View with portions broken away showing an alternative arrangement of apparatus for actuating the type pallets and a keyboard transmitter disabling function mechanism and latch;

Fig. 3 is a View partly in elevation and partly in section showing details of the type pallet operating mechanism and of the type wheel, the type pallet operating mechanism being shown in elevation and the type wheel being shown in section; and

Fig. 4 is a vertical sectional view through a keyboard transmitter mechanism showing the transmitter shunt contact unlatching mechanism.

Referring now to the drawings and particularly to Fig. 1, the reference numerals I6 and I1 designate generally the typing unit and keyboard transmitter unit, respectively, of a printing telegraph apparatus embodying the present invention. The keyboard transmitter unit I1 is generally similar to the transmitter disclosed in copending application Serial No. 77,796, led May 4, 1936 by Albert H. Reiber, and typing unit I6 embodies improvements on the typing unit disclosed in the copending application.

The foundation of the keyboard transmitter unit is the base casting I8 to the forward vertical wall of which is secured a slotted comb I9. A plurality of key levers 2l are pivoted within the casting I8 for rocking movement in a vertical plane, and these key levers protrude from the interior of base I8 through a slot in comb I9. The key levers 2I are provided with keytops 22 and are arranged to impart characteristic-settings to permutation code bars contained within base I8 as fully disclosed in Patent No. 1,595,472 granted August 10, 1926 to Howard L. Krum. To the code bars are articulated lock levers 23 pivotally supported intermediate their ends and projecting above the upper surface of base casting I8 through apertures therein. The lock levers 23 are therefore subject to permutative setting by the code bars under the control of key levers 2 I.

The upwardly projecting portions of the lock levers 23 are disposed between brackets 24 and 26 secured to base I8, and aligned with each of the lock levers 23 is a contact controlling lever 21, the levers 21 being pivotally supported by a pivot rod (not shown) extending between brackets 24 and 26. A transmitting contact spring 28 individual to each of the levers 21 is mounted between insulating Strips upon laterally extending portions of brackets 24 and 28, as indicated at 29. The upper end of each contact spring 28 engages a gooseneck portion of lever 21 and the flexing of Contact spring 28 into and out of engagement with a shorter associated contact spring is controlled by gooseneck lever 21. The rocking of the gooseneck lever 21 is, in turn, controlled by the lock levers through blocking lugs (not shown), a lever 21 being unblocked when its corresponding lock lever is presented in extreme clockwise position and being blocked when its corresponding lock lever is in extreme counterclockwise position.

Bracket 24 and another bracket designated by the reference numeral 3I rotatably support a signal transmitting distributor shaft 32. Near one end shaft 32 has secured thereto a gear 33 to which rotation is continuously imparted by another gear as will presently appear. Adjacent to gear 33, shaft 32 has secured thereto the driving element 34 of a jaw clutch. A driven clutch element 36, slidable upon shaft 32, is keyed to a cam sleeve 31 and is urged toward clutch driving element 34 by a compression spring 38. A pivoted clutch throwout lever 39 normally holds driven clutch element 36 out of engagement with driving element 34 against the force exerted by compression spring 38. Clutch throwout lever 39 has an arm 4I which terminates substantially in engagement with an abutment screw 42 carried I 2 I, it rocks bell crank 43 clockwise which, in turn,

trips clutch throwout lever 39 and permits spring 38 to shift driven clutch element 36 into engagement with driving element 34. As link 41 is moved forward, it is cammed downwardly by cooperation of a cam projection 48 with the head of a screw 49 carried by a forwardly extending portion of bracket 26. The camming of link 41 downwardly permits the free end of arm 44 of bell crank 43 to escape from lug 46 so that bell crank 43 may return immediately to its extreme counterclockwise position and permit clutch throwout lever 39 to return immediately into position for arresting the clutch comprising elements 34 and 36 at the conclusion of one revolution thereof, even though a key lever should be held depressed and link 41 retained in its forward position for a prolonged interval of time. 'I'hus the operation of cam sleeve 31 by the jaw clutch is confined to single revolution in response to each operation of a key lever. A tension spring 5I maintains engagement between cam projection 48 of link 41 and the head of screw 49.

The cam sleeve 31 carries a lock bail operating cam 52 and a plurality of impulse timing cams 53. Cam 52 controls the operation of a lock bail 54 pivotally supported by brackets 24 and 26, lowering the bail into blocking relation to the lock levers 23 as the cam sleeve 31 begins to rotate, and lifting it at the end of a cycle. The function of the lock bail 54 is to prevent the shifting of lock levers 23 during a cycle of rotation ofy the impulse timing cams 53 and thus preventing mutilation of a signal combination established by the depression of a key lever 2i. Each of the cams 53 is aligned with one of the transmitting contact control levers 21 and is engaged by a portion of the aligned lever. Each of the cams 53 has a notch 56 in the periphery thereof which, when presented to the associated transmitting contact control lever 21, releases that lever for rocking movement in counterclockwise direction, and the lever 21 rocks unless restrained by its associated lock lever 23. The recesses 56 in the several cams 53 are arranged spirally about the cam assembly so that the levers 21 are released for rocking movement successively. When a lever 21 is permitted to rock counterclockwise by its cam 33, its contact spring 21 iiexes into engagement with the associated short contact spring and a current impulse is impressed upon the telegraph line, the duration of which corresponds to the interval in which the lever 21 remains in its counterclockwise position. The cams 53 thus distribute to the telegraph line the signal impulses corresponding to a character represented by a key lever depressed. One of the contact controlling levers 21 has no lock lever associated with it and operates invariably once in each cycle of operation of the transmitting cam for impressing on the line the stop impulse.

The principal foundation element of the typing or receiving unit is a casting which mounts on the keyboard base I8 and has a portion 6I located centrally of the base I8 and a portion 62 extending transversely of the base I8 in proximity to the rear edge thereof. Thumb screws are employed for securing the casting comprising portions 6I and 62 to the base I8, one of those screws being indicated at 63. A secondary casting 64 extends transversely of the keybo-ard base I8 and is secured to portion 62 of the primary casting by any desired means, such as screws. The primary casting supports all of the power driven shafts, the operating cam assemblies, the selector mechanism, the printing mechanism, and the ribbon feed mechanism. The second-ary casting 64 supports the platen carriage and associated mecha.- nism, the signal bells, and a set of levers by which various functions are performed.

The primary selector mechanism which integrates the signal combinations generated in the keyboard transmitter mechanism, hereinbefore described, or in a remote transmitter, is indicated generally by the reference numeral 66 and is generally similar to the primary selector mechanism disclosed in the hereinbefore identified copending application of Albert H. Reiber, Serial No. 77,796. The principal elements of the selecto-r mechanism 66 are a selector cam assembly 61, a selector magnet 68, and a sword and T-lever assembly 69, the last mentioned assembly as well as the selector magnet being supported by a mounting plate 1I carried by the forwardly extending portion 6I of the primary casting. The selector cam assembly 61 is carried by the upper end of a vertically positioned shaft which is rotatably supported in bearing blocks 12 and 13. IThe selector cam assembly 61 has anges 14 secured thereto at opposite ends, and in spaced relation to each fiange 14 is a flange 16 secured to the shaft which supports the cam assembly 61. A friction disc 11 occupies. the space between each of the flanges 14 and the adjacent flange 16. Considerable friction isgenerated between the discs 11 and those positioned on either side of them so that selector cam assembly 61 will rotate with its supporting shaft except when restrained under the control of selecto-r magnet 66, as is well known in this type of single magnet selector mechanism. f

Just above the point at which it enters lower bearing block 12, the shaft has secured thereto a gear 16. An electric motor (not shown) drives a pinion which meshes with gear 18 so that the shaft to which the gear 18 is secured is continuously rotated. It may be added at this point that a gear 19 carried by a stub shaft meshes with gear 16 and that a spiral gear 8l also secured to the stub shaft meshes with gear 33 carried by the transmitter shaft 32. Thus rotation is imparted to the transmitting distributor shaft 32 from the motor pinion through gears 18, 19, 8I, and 33.

The sword and T-lever mechanism 69 is actuated under the joint control of selector cam assembly 61 and the selector magnet 68 to interpret or integrate a series of impulses-representing a signal combination preparatory to setting T- levers 82 in accordance with the signal combination. Each of the T-levers 82 engages one arm of a transfer bell crank 83, the other arm of which is articulated to one of the notched code discs of a code disc selector mechanism indicated generally by the reference numeral 84. y

The code disc selector mechanism 84 has a circular arrangement of vertically positioned stop pins 86 which project through slots in the topmost plate of the mechanism. Stop pins 86 are biased inwardly radially of the code disc selector mechanism and near their upper ends they rest against the edges of shiftable notched code discs as is fully disclosed in the copending application of Albert H. Reiber, Serial No. 77,796. 'Ihe notching of the code discs is such that for any permutative setting of the discs under the control of T-levers 82 one only of the stop pins 86 finds presented to it an alignment of notches, whereupon the pin therefor enters the alignment of notches under the iniiuence of its biasing spring, its upper end moving inwardly. A type wheel stop arm 81 clamped to type wheel shaft 88 is of .such length that in revolving, it just clears those of the stop pins 86 which are held in their outermost positions by the code discs, but finds blocking its path any pin 3S which has entered an alignment of notches in the periphery of the code discs. The type wheel shaft 88 extends downwardly through the code dise selector mechanism 84 coaxially thereof and receives a continuous torque from the driving moto-r through any convenient means, such as a gear carried by the shaft 88 and connected thereto by friction discs, the gear being continuously in mesh with the motor pinion. With this arrangement, the shaft 88 is always prepared to rotate and is free to do so when any stop pin 86 which had been previously selected is moved out of the path of the stop arm 81 upon the resetting of the code discs. With this arrangement, shaft 88 may be arrested in any angular position in which stop arm 81 encounters a stop pin 86.

The setting of the T-levers 82 according to the operation of the sword lever mechanism 69 is controlled by a transfer bail 9| which is cam operated as will presently appear. Transfer bail 9| is pivotally supported by an upper mounting screw 92 and by a lower mounting screw which does not appear in Fig. 1. Transfer bail 9| is biased in counterclockwise direction by tension spring'93 and has oppositely extending arms 94 and 95, the former of which is only partially indicated in Fig. 1 but which supports transfer springs, as is clearly indicated in the copending application Serial No. 77,796, and the latter of which carries a locking blade 91 that cooperates with extensions 90 of T-levers 82. Locking blade 91 ordinarily blocks the extensions 98 of T-levers 82 whether they be presented in extreme clockwise or counterclockwise position. The rocking of transfer bail 9| in clockwise direction to eect the resetting of T-levers 82 is accompanied by withdrawal of locking blade 91 out of the path of movement of T-lever extensions 98. When the transfer has been completed, transfer bail 9| returns to its extreme counterclockwise position and locking blade 91 is restored to locking position with respect to extensions 98.

The front portion 6| of the primary foundation casting for the typing unit has secured thereto spaced brackets |0| and |02. A shaft |03 is rotatably supported in vertical position between brackets |0| and |92. Shaft |03 has secured thereto near the lower end a gear |34 which permanently meshes with a gear |00 supported by gear 18 and secured thereto by any desired means, such as screws. The hub of` gear |04 has secured thereto the driving portion |01 of a positive engagement clutch mechanism, the driven portion of which is indicated by the reference numeral |08. The driven element |08 may be of the type disclosed in copending application Serial No. 165,437, filed September 24, 1937, by B. F. Madsen, having in its periphery a groove designated |09 in the present application, which receives the portion of the clutch throwout lever |'|2. The portion v| of the clutch throwout lever ||2 confines driven clutch element |08 to substantially complete engagement with driving element |01 during a cycle of operation following the tripping of the clutch, and prevents acceleration of the driven element of the clutch from the speed imparted to it by the driving element |01, should any torque generated by negative load resulting from the interaction of a cam follower and its cam be applied to the driven clutch element |08. Driven clutch element |08 is slidably splined or keyed to a cam assembly sleeve 3 `and is urged into engagement with driving element |01 by compression spring ||4.

Clutch throwout lever ||2 is carried bythe lower end of a pivoted bail IIB, the upper pivot of which is indicated ||1. At its upper end, bail H6 is provided with an arm ||5, the free end of which is disposed in the path of the lowermost cam projection |20 of selector cam assembly 61. Bail I |6 is biased in counterclockwise direction by tension spring |2|. When cam projection |20 on selector cam assembly 61 encounters arm H5 of bail IIS, the bail is rocked in clockwise direction, thus withdrawing clutch throwout lever |`|2 from restraining engagement with the driven clutch element |08 of the clutch on the front shaft, and permitting driven element |08 to move into engagement with driving element |01 whereby rotation is imparted to cam sleeve H3.

Cam sleeve |3 supports three cams designated IIS, H9, and |25. Cam ||9 is engaged by a follower roll |22 carried by an arm |23 secured to transfer bail 9|. The direction of rotation of cam sleeve ||3 is counterclockwise and cam |29, in being rotated, imparts clockwise rotation to arm |23 and therefore to transfer bail 9|. Transfer bail 9|, as previously set forth, effects the permutational rearrangement of T-levers 82 and therefore the notched code discs in the code disc selector mechanism 34 in accordance with a signal combination which has been integrated in the sword lever mechanism 69.

As previously set forth, there is a shaft rotatably supported in vertical position by bearing blocks 12 and 13 to which the gear 18 is secured.

Below bearing block 13 the shaft has secured thereto the driving element |24 of a positive drive clutch, the driven element of which is indicated |29. Driven element |29 is slidably splined or keyed to a main cam assembly |30 and is urged into engagement with driving element |24 by a compression spring |26. The engagement and disengagement of the elements |24 and |29 of the main cam assembly driving clutch mechanism is controlled by a pivoted clutch throwout lever |21 to which is secured an arm |23 that extends forwardly of the typing unit and terminates in the path of the apex of cam |8 carried by cam sleeve ||3 on the front shaft. As indicated n Fig. 1, in which the clutch mechanism on the shaft and on the main cam driving shaft are shown in their rest positions, the rest position of the apex of cam I8 is a small angular distance in counterclockwise direction from the end of arm |28 which effects the tripping of the main cam clutch comprising elements |24 and |29. Since, as previously stated, cam cylinder I3 rotates in counterclockwise direction, it will be apparent that cam ||8 operates upon arm |28 to effect the tripping of driven clutch element |29 just before cam I8 reaches the end of a cycle of operation.

The bracket |0| which rotatably supports the upper end of shaft |03 pivotally supports a, bail |3|, the pivot being indicated |32. The bail |3| supports a cam follower arm which has been omitted from the showing 'of Fig. 1 for the reason that it would conceal substantial portions of the main cam assembly |30 carried by the rotatable shaft which is supported in bearing blocks 12 and 13. The cam follower arm carries at its free end a follower roll which engages cam at a point between cam assemblies ||3 and |24. The contour of cam |25 comprises a smooth gradual rise and a sharp drop-off, the drop-off being indicated by a'reference numeral |33. As cam |25 rotates counterclockwise, it shifts its follower roll away from the axis of shaft |03 and thus imparts a counterclockwise rotation to bail I3 I. In the rest position of cam |25, the drop-off |33 is a small angular distance beyond the point of engagement of the cam follower roll with cam |25. The tendency of the cam |25 therefore is to permit bail |3| to return sharply to its extreme clockwise position just before cam |25 reaches its rest position. However, as will presently appear, a cam included in the cam assembly assumes control of bail |3I just before the sharp drop-oir |33 in cam |25 is presented to its follower, and the cam in cam assembly |33 holds bail |3I in extreme counterclockwise position for a predetermined interval and thereafter controls the restoration of bail |3| to its extreme clockwise position.

Bail |3| has integral therewith an arm |34 which extends toward the rear of the typing unit and terminates in a spring hanger hook |36. Hook |36 supports one end of a tension spring |31, theopposite end of which is connected to an arm |38 of a type wheel supporting frame |39.

Frame |39 is provided with a vertically disposed slot |4I, through which extends a stud |42 supported by a portion of the frame of the typing unit. At the top, frame |39 has a horizontally extending portion |43 through which type wheel shaft 88 passes and in which is rotatably held the hub of a type wheel |44. vertically disposed guide pins |46, only one of which appears in Fig. 1, are supported by a stationary bracket |41 at the top of the typing unit and pass through apertures in the horizontal portion |43 of type wheel supporting frame |33. The pins |46 and the cooperating elements comprising slot |4| and stud |42 permit oscillatory movement of frame |39 vertically, and guide the frame in that movement. Frame |39 is provided with an abutment screw |48 against which arm |34 of bail |3| rests when the bail |3| is in extreme clockwise position and frame |36 is in the lowermosi-l position. When bail |3| is rocked in counterclockwise direction by cam |25, bail arm |34 tends to move out of engagement with abutment screw |48 and spring |31 tends to be distended. Spring |31, in turn, lifts frame |30, and thus type wheel |44, the normal position of which is below the printing line, is elevated so as to bring character elements carried upon the periphery of the type wheel into position to effect printing in line upon a page carried in engagement with cylindrical platen |43. When bail |3I is restored to its extreme clockwise position, arm |34 engages abutment screw |48 and restores frame |39 to its lowermost position which, in turn, restores type wheel |44 to its lowermost position, whereby each -character becomes visible immediately after being printed.

As previously set forth, main cam sleeve |30 is set in operation by the tripping of clutch throwout lever |21 by cam ||8 included in front cam assembly ||3 just before cam ||8 reaches its rest position. The uppermost of the cams carried by cam assembly |30, designated |5I, is engaged on the periphery thereof by -a follower roll |52 carried at the end of a lever |53 which is pivoted at |54. Lever |53 has integral therewith an arm |56 which is provided near its outer end with a plurality of spring connection apertures |51. Any one f of the apertures |51 is adapted to receive one end of a tension spring |58, the other end of which is supported by a spring post |59. Spring |58 biases lever |53 in counterclockwise direction, thus urging cam follower roll |52 into engagement with the periphery of cam |5I. The several spring mounting apertures |51 in arm |56 of lever |53 are at different distances from spring post |59 so that the tension exerted by spring |58 and therefore the torque applied to lever |53 may be Varied.

A print hammer operating bail I6| is pivotally supported -by pivotl |54 and coaxially mounted pivot |62. At its lower end, bail |6| is provided with an arm |63 which supports adjustable abutment screw |64 and also one end of a tension spring |66. The inner end of abutment screw |64 engages an arm |61 of lever |53 and the rearmost end of tension spring |66 is also connected to arm |61 of lever |53. With this arrangement, bail |6| tends to occupy extreme clockwise position with respect -to lever |53, the extremity of the position being determined by abutment screw Print hammer operating bail I6| has integral therewith at its upper end a lever arm |68. At its free end, lever arm |68 is loosely articulate-d to a print hammer |69. Print hammer |69 extends between ribbon spools I1I, rotatably mounted upon a ribbon feed mechanism supporting plate |12. Print hammer |69 is provided with upper and lower arms |13 and |14, respectively, which are disposed in the same vertical plane. Lower arm |14 enters a slot in a bracket |16, carried by ribbon feed mechanism foundation plate |12, and by means of slotted bracket |16, print hammer |69 is held in a vertical plane and is guided in reciprocatory motion imparted by arm |68 of bail |6I. The upper `arm* |13 of print hammer |69 is longer than the lower arm |14 and extends across the periphery of type wheel |44 and across the upper end of type wheel shaft 88. At its free end, arm |13 is provided with a depending portion |11 which, in turn, is provided with an arm |18, the location of which is in alignment with the foremost portion of platen |49, which portion is at the level where printing occurs. Print hammer |69 is provided in its lower edge with a shallow recess |10, the base of which rests upon and slides upon a retainer bar |15 secured to ribbon mechanism base plate |12. The motion of print hammer |69 to effect printing is limited by engagement of one end of recess |10 with bar |15, and the restorational motion may, if desired, be limited by engagement of the other end of recess |10 with bar |15.

The print hammer |89 may be lifted out of its position above the type wheel |44 to permit adjusting or changing the type wheel, by springing' the free end of print bail arm upwardly until the rearmost end of recess |10 clears bar |15, whereuponarm v|14 of the print hammer may be drawn clear of slotted bracket |16, and the print hammer may be rotated upwardly in a vertical plane about its pivot of articulationwith bail arm |68.

Type wheel |44 may be generally similar to the type wheel disclose-d in the hereinbefore identied application of Albert H. Reiber, Serial No. 77,796, and also in application Serial No. 77,794, filed May 4, 1936, by Howard L. Krum et al. As shown in those copending applications and as clearly indicated in Fig. 1 of the present application, type wheel |44 is provided with a plurality of radially disposed type pallets |19 which are reciprocably mounted in radial slots in type wheel |44, and are provided at their outer ends with type elements |8I. There may be two superposed rows of type pallets |19, and by means of the lifting of type wheel supporting frame |39 by lever |34, either of the rows of type pallets may be brought into alignment with rearwardly presented portion |18 of print hammer |69. For any angular position of arrestment of type wheel |44 by the cooperation of type wheel stop arm 81 with a selected stop pin 86, two of the type pallets |19 will be directed toward platen |49 in the same vertical plane as print hammer |69. According to the distance that type wheel |44 has been lifted by lever arm |34, the distance being controllable, as will appear later, one or the other of the type pallets |19 will be disposed directly in the path of portion |18 0f print hammer |69.

Cam |5|, in its normal or rest position, holds print bail operating lever |53 in extreme clockwise position in opposition to the tension of spring |58. Spring |66 holds print hammer bail IGI in extreme clockwise position with its abutment screw |64 in engagement with arm |61 of print bail operating lever |53. Thus, print hammer |69 is held in retracted position. At a predetermined time in the operation of cam I5 a sharp drop-off is presented to follower roll |52 of print bail operating lever |53. When the drop-off is encountered, lever |53 is rocked sharply in counterclockwise direction by spring |58. Lever |53 imparts counterclockwise movement to bail |6| through abutment screw |64. The angular distance through which lever |53 rocks, as cam follower |52 descends to the lowest or innermost point on the periphery of cam |5| is just short of sufficient to drive print hammer |69 positively against the type pallet |19 aligned therewith. However, the inertia of bail |6| and print hammer |69 causes spring |66 to yield and abutment screw |64 to move out of engagement with arm |61. Thus print hammer |69 overtravels or moves a greater distance than it would if positively interconnected with lever |53, the overtravel being caused by the inertia of bail |6| and print hammer |69, and being permitted by spring |66.

As soon as the energy generated b-y the inertia of bail 6| and print hamm-er |69 has been eX- pended, spring |66 withdraws print hammer |69 in the direction of its retracted position until abutment screw |64 returns into engagement with arm |61 of lever |53. The remainder of the movement of print hammer |69 to its rest position is effected by the restoration of lever |53 toits eX- treme clockwise position by cam |5|. The overtravel in the movement of print hammer |69 is sufficient to reciprocate the aligned type pallet |19 radially of type wheel |44 to effect printing. During the period of overtravel and restoration, the free end of arm |13 of print hammer |69 is presented between the type Apallets adjacent to that which is being operated, so that the type wheel |44 could not be rotated, even if permitted to do so by arm 81, due to the fact that interference between arm |13 of print hammer |69 and adjacent unoperated type pallet would occur. Spring |66 withdraws print hammer |69 from a position of interference with unoperated type pallets much more rapidly than it could be withdrawn if positively connected to print hammer bail operating lever |53. Thus, with the arrangement hereinbefore described, the print hammer |69 is projected and retracted in the shortest possible interval of time so that more time may be allowed for the rotation of type wheel |44 to the position corresponding to the next selection.

In a preceding paragraph, the lifting of the type wheel to bring either of its two rows ofl type pallets into printing position was described. rThe lifting is accomplished by the counterclockwise rocking of bail |31 which has an arm |34 interconnected with the type wheel supporting frame |39 by spring |31. It was stated that the lifting of the type wheel supporting frame |39 is effected by a cam |25 on the front shaft. it was also stated that the lowering of type wheel supporting frame |39 is controlled by a cam included in the cam assembly |39 on the main shaft. This cam is indicated by the reference numeral |36, and is of the internal species having its cam surface on the inside of a depending peripheral flange. The internal cam surface is engaged by a follower roller carried at the free end of an arm |81, secured to type wheel lifting bail |3|. Spring |31 biases bail 3| in clockwise direction as previously set forth and, in so doing, urges the follower roller carried by arm |81 to seek engagement with the internal cam surface of cam |66. Cam |86 does not have a restricting channel, so that the follower carried by arm |81 is free to be moved away from engagement with the interior of the depending flange of cam |85 when bail |3| is rocked in counterclockwise direction by cam |25. During the initial stages of the lifting of frame |39 by cam |25, cam |86 may be stationary.

About the time that cam |25 has rocked bail |3| toits extreme oounterclockwise position, and before the drop-off of the cam is presented to its follower roller, the innermost portion of the cam surface of cam |86 is presented in engagement with the follower roller carried by cam follower arm |81. During the engagement of the follower roller carried by arm |81 with whatever dwell there may be at th-e innermost portion of the internal cam surface of cam |86, bail |3| will be held in extreme counterclockwise position and lever arm |34 will `be held in a corresponding position. As cam |96 continues to rotate and the receding cam surface is presented to its follower (the recession being radially away from the axis of the cam), bail 3| will be restored by a controlled motion to its extreme clockwise position, and type wheel supporting frame |39 will be restored to its lowermost position to render visible the character just previously printed. It will be apparent that when the type wheel frame |39 is being elevated, the cam follower, by means of which the lowering of the frame will subsequently be controlled, is moved out of engagement with its cam surface, and that when the frame |39 is being held in elevatedv position, and is being lowered, the cam follower by which its elevation was accomplished will be held out of engagement with the elevating cam,

Of the principal mechanisms of the typing unit I6, there remains for consideration only the function mechanism. This mechanism is, in general, similar in construction and operation to the function mechanism disclosed in the copending application of Albert I-I. Reiber, Serial No. 77,796.- The function mechanism may be understood to include those mechanisms by which such operations shift, unshift, carriage return, line feed, signal lbell operation, and transmitter disablement are selected and accomplished. Those functions which are materially different from the corresponding functions, as disclosed in the copending application of Albert H. Reiber, Serial No. 77,796, and which will be described in detail, are shift and unshift, by means of which selection of characters in the letters or figures bank of type pallets is accomplished.

The selection of a function is accomplished by means of a testing mechanism which is cam controlled. Since the testing operation can be conveniently performed by a groove or channel cam, a channel I9| is provided in the upper surface of print bail operating cam ISI. A cam follower, which could not be shown in Fig. 1, is fitted into the groove or channel 19| in cam |5I, and the follower arm is part of `a'bail |92 which is operated to test for the selection of functions, and to condition in accordance with the selection one or more of a plurality of function bars, indicated generally by the reference numeral |93. The manner in which the presence of a function is tested and in which the function bars |93 are conditioned is fully disclosed in the copending application of Albert H. Reiber, Serial No. 77,796.

The function `bars |93 are pivotally mounted upon rod |94. Rod |96 is supported between spaced arms I 96 and I 91, which comprise a function bail pivoted upon -pivot rod |99. The lower arm |91 of the function bail has integral therewith an arm |99 at the free end of which is supported a cam follower roller 20|. A function cam 202, carried by the main cam sleeve |30, has its periphery engaged by roller 20|, and when cam 202 occupies rest position, arm |99 and the function bail comprising arms |96 and |91 are disposed in extreme clockwise position.

At their free ends, the arms |96 and |91 support a spring post 203 to which is hooked one end of each of a plurality of tension springs 204. Each of the springs 204 has its other end connected to one of the function bars |93. Thus, the function bars |93 are biased in counterclockwise direction, and movement of any of them in clockwise direction is opposed by its particular tension spring 204.

The conditioning of function bars |93, under the control of bail |92 in response to a function selection, is manifested by rotation of one or more of the function bars |93 through a small angular distance in clockwise directicn. Such rotational movement brings the conditioned function bar out of alignment with the unselected function bars and into position to initiate or perform its assigned function. Immediately after the conditioning of one of the function bars |93, cam 292 rocks its follower arm 20| `and the function bail comprising arms |95 and |91 in counterclockwise direction. Since the function bars I 93 are pivot,- ally mounted upon rod |94, carried by bail arms |93 and |91, they are moved endvvise toward the rear of the printer as cam follower roller 20| is moved to its outermost position with respect to cam 202. Those of the function bars |93 which have not been conditioned by being rocked in clockwise direction are reciprocated idly while one conditioned function bar |93 initiates o-r pe-rforms the assigned function as a resultof the reciprocatory movement. The rod |94, carried by function bail arms |96 and |91, also is pivotally engaged by a spacing pawl 206 which is reciprocated to effect spacing of the platen carriage as the function bars |93 are reciprocated rearwardly of the printer. The spacing operation and the performance of the several functions excepting shift and unshift are sufficiently similar to those disclosed in the copending application Serial No. 77,796, that it is considered unnecessary to describe them in detail here. However, the shift and unshift functions will now be described.

The hereinbefore identified stud |92, which guides the type wheel supporting frame |39 in its upward and downward movements, extends through a horizontally extending slot in a slide member 201. The slide member 201 is also provided with an open ended slot 299 through which extends a screw 209, carried by the frame of the typing unit. The stud |42 and screw 209 support the slide member 291 and guide it throughout a limited sliding movement forwardly and rearwardly of the typing unit.

The slide member 201 has integral therewith a vertically extending arm 2| I. The yarrn 2II is provided near its upper end with a step cut aperture 2 I 2. By virtue of the step cutting, two Iabutments or stop surfaces are provided, the lower of which is indicated by the reference numeral 2|3, and the upper of which is indicated 2M and is the upper end of the aperture 2|2. The type wheel supporting `and lifting frame |39 has adjustably secured thereto a bracket 2|6, which has an arm 2|1, extending into the aperture 212 of the slide member 201. When the type wheel lifting frame |30 is lifted by bail arm |34, operating through spring |31, arm 2|1 of bracket 2|6 may encounter either of the stop surfaces 2|3 or 2I4, depending upon whether the slide member 201 is presented in its rearmost or foremost position, and thereby the type wheel lifting frame |39 will be arrested in either of two positions of elevation while bail arm |34 continues to be rocked to its extreme counterclockwise position. When the type wheel lifting frame |39 is arrested by the lower stop surface 2I3 of slide member 201 the upper row of type pallets carried by type wheel |49 is presented in alignment with the operating extension |18 of print hammer |99, and when the frame |39 is permitted to be lifted until its arm 2I'I encounters the uppermost stop surface'2i4,

the lower row of type pallets will be presented in alignment with the print hammer |39, and with the character impression level of the platen |29.

The movement of slide member 201 from one to the other of its two positions is accomplished by two levers pivoted upon stud |42, one of the levers being pivotally supported between slide member 201 and the frame elements which support stud |42 and which, therefore, is behind slide member 201 and cannot be seen in Fig. l, and the other of which is pivotally supported between slide member 201 and type wheel lifting frame |39 and is indicated by the reference numeral 218 in Fig. 1. A screw 2|9 establishes a pivotal interconnection between the slide member 201 and its operating lever 2 I8. Lever 2| 8 is provided with a depending finger 22|. The rst and second of the function bars |93, counting from the top, each have extending laterally therefrom a lug, one of which appears in Fig. l and is indicated by the reference numeral 222. The depending finger 22|, of lever 2|8, occupies a position directly in the path of lug 222 when the function bar which carries lug 222 has beenconditioned for function performance by being rocked in clockwise direction preparatory to being moved endwise by cam 202,

operating through arm 20| and bail arms |96 and |91. When lever 2I8 is in its extreme counterclockwise position, which is the condition when slide member 201 occupies the rearmost of its possible positions, finger 22| is disposed substantially at the limit of movement of lug 222 so that it will not be affected if the function bar by which lug 222 is carried is conditioned and reciprocated. When, however, the slide member 201 occupies the foremost position, lever 2 I9 will be presented in extreme clockwise position and its depending finger 22| will be positioned to be engaged by lug 222, early in the cycle of movement of that lug rearwardly of the typing unit. Under these conditions counterclockwise movement of lever 2|8 by lug 222, as it moves rearwardly of the typing unit, will result in rearward movement of slide member 201 which is articulated t0 lever 2| 8 by screw 2| 9, whereby slide member 201 will be shifted to its rearmost position with stop surface 2|3 in the path of arm 2|1 carried by type wheel lifting frame |39. It will be understood that the timing of the apparatus is such that type wheel supporting frame |39 is held lowered by bail arm |34 when slide member 201 is shifted so that there shall be no interference between arm 2|1 and the step-cut portion of aperture 2|2 during the movement of slide member 201.

The restoration of the slide member 201 to its forward position is accomplished by the lever which corresponds to lever 2|8 and which is pivoted between slide member 201 and the frame member which supports stud |22 so that it does not appear in Fig. l. A screw 223 establishes a pivotal connection between this lever and the slide member 201. This pivotal interconnection is above stud |42 so that when` the lever is rocked in counterclockwise direction, the slide member 201 will be moved forwardly of the typing unit to its foremost position. The lower end of the lever which is pivoted to slide member 201 at 223 may be similar to the lower end of lever 2|8 so that when it is in extreme clockwise position, it will be disposed in the path of the laterally eX- tending projection of that one of the function bars |93, the function of which is to shift the slide member 201 to its foremost position to permit the type wheel lifting frame |39 and the type wheel |44 to be lifted to their uppermost 'position whereby printing may be effected from the lower row of type pallets.

It will be apparent from the foregoing description of the levers which control the shifting of slide member 201 that both of these levers effect control by being rocked in counterclockwise direction, one being operative to shift the slide member 291 rearwardly and the other being operative to shift it forwardly. It will also be apparent that as either is rocked in counterclockwise direction by its assigned function bar |93, the motion which it imparts to the slide member 291 will cause the other lever to be rocked in clockwise direction so that they will be presented alternately in position to be operated by their respective function bars.

In addition to operating the function levers |93 and the spacing pawl 206, the function bail also operates a ribbon feed lever 226. This lever is pivoted upon a stud 221 fixed to a stationary portion of the typing unit and its lower end engages the arms |96 and |91 of the function bail. At its upper end, lever 226 is Iarticulated to a link 228 which has a slot in which is disposed one end of a ribbon feed lever 229. The ribbon feed mechanism which is operated by lever 229 may be substantially identical with that disclosed in the copending application of Albert H. Reiber, Serial No. 77,796. The ribbon feed mechanism supporting plate |12 supports pairs of vertically disposed pins 23| which serve as guides for the inked ribbon 232, and there is also a semicircular ribbon guide which is supported by the type wheel lifting frame |39 in spaced relation to the type wheel |44 between the type wheel and the platen |49. Thus, the ribbon guide 233 is lifted each time the type wheel |44 is lifted, and a portion of the ribbon 232 is always positioned between the type wheel |44 and the platen |49 so that inked type impressions may be produced upon a page carried by platen |49.

The platen |49 isrotatably supported by the opposed ends of a carriage 236. The carriage is supported for movement transversely of the typing unit by rails, one of which is indicated as 231, secured to the rear casting member 64. The casting 64 also supports near the top thereof a bracket 230 which has a threaded aperture in coaxial relation to the platen |49. A bushing 239 threadedly engages the aperture in bracket 238 and rotatably supports a square rod 24| which enters platen |49 through one of the hubs threin and passes through a square portion of a tube which extends from end to end of the platen |49. The square shaft 24| is of sufficient length that it may extend into or through the square portion of the tube on the interior of platen |49 in any position which carriage 236 may occupy in its travel back and forth upon its supporting rails. Square shaft 24| has secured thereto a crank 242 which may be rotated manually to impart rotation to square shaft 24| and, through its cooperation with the square portion of the tube into which it extends, rotation may be imparted to platen 49.

Carriage 236 also supports a paper guiding plate or basket 243 which is disposed below the platen for guiding a page in the printing position and which, in turn, supports pressure rolls 244 and paper guide fingers 246. Carriage 236 may have associated therewith character spacing mechanism and line feeding mechanism in accordance with the disclosure of the copending application of Albert H. Reiber, Serial No. 77,796. A rotatable drum 241 is provided for housing a carriage return spring. A carriage return belt 248 has one end secured to the periphery of drum 241 and the other end secured to carriage 236.

Terminal blocks and slip connections are provided for connecting the various electrical circuit elements in the keyboard transmitter mechanism and in the typing unit to external circuits. The reference numeral 25| indicates a terminal block which is mounted on the keyboard base casting |8 behind the typing unit. Terminal block 25| has terminals 252 individually engaged by slip connection tongues 253 carried by a slip connection block 254. Slip connection block 254 is secured to the rear portion 62 of the primary typing unit casting below the secondary or carriage supporting casting 64. The contacts 252 and tongues 253 may form electrical connections between the electromagnet 68 carried by the typing unit and the transmitting contact springs 21 carried by the keyboard base and between the selector magnet and external circuit. Thus, the secondary casting and all of the elements which it supports may be removed from the typing unit without disturbing the electrical connection between the selector magnet 68 and the transmit- Vfl ting contacts and between the external circuit and both the selector magnet and the contacts.

Also the entire typing unit may be removed from' the keyboard base by removal of the thumb screws 83 whereby the slip connection tongues 253 will be removed from engagement with contacts 252 without disturbing the electrical connections between the transmitting contacts and external circuit,

The general operation of the typing or receiving unit hereinbefore described is as follows: Permutation code signals impressed upon a telegraph line to which the receiving unit is connected enter the receiving unit at terminals 252 and slip connection 253 and are impressed .upon the selector magnet 68. Gear 18 and the shaft which it drives, being in operation, selector assembly 61 which is friction driven is released for a cycle of operation by the start impulse of a signal combination in accordance with the well-known practice employed in the operation of single magnet selector mechanisms controlled by start-stop signals. As the selector cam assembly 61 rotates, the sword levers contained in the sword lever mechanism 69 are set in characteristic positions according to the signal combination received. Just before the selector cam assembly 61 completes a cycle of rotation, its cam projection engages arm I |5 of bail I6 and rocks the bail in clockwise direction whereby clutch throwout lever |I2 is withdrawn from restraining engagement with driven clutch element |08, carried by the front shaft, whereupon the driven element |08 is shifted into engagement with driving element |01, and cam sleeve ||3 is set in operation for a cycle comprising one revolution.

The first operation performed after cam sleeve I I3 is set in operation is the clockwise rocking of transfer bail 9|, by transfer cam II9, operating through cam follower roller |22 and follower arm |23. Transfer bail 9| operates to set the code discs contained in the code disc selector mechanism 84 in correspondence with the setting of the sword levers. The shifting of the code discs to accomplish the selection of a new stop pin 86 is accompanied by the camming of the previously selected stop pin into unselected position whereby the restraint upon type wheel stop arm 81 is removed and shaft 84 and type wheel |44 rotate to seek a new stop position. At this time, the type wheel |44 is held in its lowermost position by thev type wheel lifting bail I3| and bail arm As soon as the transfer has been accomplished,`

the selector cam barrel 61 may be released for rotation to effect the setting of the sword levers according to a new signal combination. The timing of the operation of selector cam assembly 61 and of cam sleeve ||3 carried by front shaft |03 is such, with respect to the speed of operation of transmitting apparatus, in response to which this receiving mechanism is intended to operate, that the transfer has been effected before the selector cam barrel is released by the start impulse of the next signal combination.

A predetermined interval after the transfer operation has been performed, cam |25 begins to rock type wheel lifting bail |3| in counterclockwise direction and the type wheel |44 is elevated into printing position. The position in which the type wheel will be arrested will be determined by the position occupied by slide member 201. Bail |3| will, however, be rocked to eX- treme clockwise position regardless of the position in which type wheel |44 is arrested, spring |31 yielding to permit the motion of bail I3| to be completed.

A short angular distance before lcam |25 has rocked bail I3I to extreme counterclockwise position, cam H8, carried by cam sleeve ||3, engages clutch throwout lever |28 of the clutch which comprises driving element |24 and driven element |29 on the main shaft or inner cam shaft, whereby the main assembly |30 is set in operation. By the time cam |25 has rocked type wheel lifting bail |3| to extreme counterclockwise position, internal cam |86, included in the main cam assembly |30, has assumed control of its follower arm |81, which is carried by bail |3 so that type wheel lifting bail |3| is held in extreme counterclockwise position after cam |25 has come to rest and has relinquished control over bail |3|.

The front shaft may be rotated at the same speed as the main shaft so that in the reception of signals continuously transmitted, the cam sleeve |I3, carried by the front shaft |03, will have a rest period between cycles of operation equal to the rest period of selector cam assembly 61 between successive code combinations. Cam sleeve |3 may, therefore, being its neXt cycle of rotation before the cam assembly |30, carried by the main or inner shaft, has completed much of its cycle of operation. While cam |86 is holding type wheel |44 elevated, and before cam sleeve |3 can have rotated sufciently far in the next cycle toy operate the transfer bail, the print cam |5| brings its sharp drop-olf into alignment with roller |52, carried by the print bail operating lever |53, whereupon spring |53 rotates lever I 53 sharply in counterclockwise direction and this movement is imparted. to print bail ISI,

which drives print hammer into engagement with the selected type pallet and which overtravels sufficiently to produce an impact between the selected type pallet and a message page carried by platen |40. At substantially the same time that print cam |5| permits print bail operating lever |53 to be rocked counterclockwise by its spring |58, cam groove |9|, in the upper surface of cam |5|, operates its associated b-ail lez, which tests for function selection as disclosed in the copending application of Albert H. Reiber, Serial No. 77,796. The effect of such testing is that a function bar |93, which corresponds to a function that may have been found to be selected is rocked clockwise through a small angular distance in opposition to its biasing spring 204, to bring it into position to initiate or' perform its function.

Since tension spring |68 is effective substantransfer of the next signal combination may be performed, the greater is the interval of time that may be allotted for rotation of the type wheel into a new stop position corresponding to the new selection and, therefore, the slower can be the speed of rotation` of the type wheel shaftv88. The maintenance of minimum rotational velocities consistent with eiiicient operation is desirable in order to minimize inertia effects.

Internal cam |86 is required to hold type wheel |44 elevated only until the print operation has been performed. As cam |5| continues to rotate and restores print bail operating lever |53 to its extreme clockwise position, cam |36 permits bail |3| and bail arm |34 to return to extreme clockwise position, the restoration not being abrupt nor viole-nt but rather being controlled and gradual.

As set forth in the description. of apparatus, cam 2512 operates function bail lever arm |99 to reciprocate the spacing pawl 266 and the function bars |23. Immediately after the printing of a character has been accomplished, the carriage 236 may be spaced to bring a blank portion of the page into position to receive the next character. If instead of a character having been selected for printing a function has been selected, and the selection evidenced. by the clockwise rocking of the particular function bar by operation of bail |92 substantially simultaneously with the operation of print bail lever |53, the apparatus is conditioned for the performance of the function. The operation of lever |99 by cam 2412 is gradual so that there is no abruptness in the performance of the function. As the function bars |93 are moved rearwardly of the typing unit by operation of function lever |59, the one of the function bars |93, which has previously been rocked into effective position initiates or performs the function such as shift, unshift, line feed, carriage return, and various other desirable functions as disclosed in the copending application' of Albert H. Reiber, Serial No. 77,796. The operation of function bail lever |99 is the last operation performed by the cams on cam sleeve 24 before the cams return to rest position, at which point, clutch throwout lever |21 separates driven clutch element |29 from driving element |24.

From the foregoing it will be observed that during the reception -of isolated or widely separated signal combinations', there occurs a train of operations for each signal combination which begins with the setting in rotation of selector cam cylinder 6l and which ends with the arrestment of main cam assembly |38. cylinder cooperates with the selector mechanism to set up the signal combination received, trips off the cam sleeve ||3 lon the front shaft, 'and comes to rest. The cams carried by sleeve ||3 transfer the signal combination to the code disc selector, elevate the type Wheel vto printing position under the control of the shift and unshift slide member 287, trip oif the main cam assembly on the inner' shaft, and come to rest. The cams on the main cam sleeve |33 effect the operation of print hammer |69, test for the presence of a function selection, control the lowering of the type wheel to its idle position, effect character spacing and the performance of any function selected, and come to rest.

When, however, signal combinations are being received at substantially maximum frequency, as is the case when the transmitter from which the signals are being received is operated by a perforated tape, or if it is a keyboard transmitter, being operated by a skillful operator, the stop time between cycles of operation of selector cam assembly 61 will be very brief. The stop time between successive cycles of the front cam cylinder H3 and the main cam cylinder |39 will be correspondingly brief, but definite phase relationships between all of the cam assemblies will be maintained. Thus, all of the cam assemblies may be rotating simultaneously, and no two of The selector cam them may be at rest at the same time. However, the operations which they control will proceed in orderly fashion exactly in accordance with the planned timing of the receiving mechanism. Any signal combination introduced at the selector magnet 68, whether relating to the printing of a character or to the performance of a function, will have become effective for the purpose for which it was introduced before the completion of the operation initiated by the selector cam assembly E?, and there will be no storage of a signal combination requiring an additional cycle of operation of the selector cam barrel for its clearing out, as is the case in some printing telegraph mechanisms, in which the transfer and printing operations are not assigned to be performed by cams included in separate cam assemblies, but are performed by cams included in a single cam assembly, and in which there is insufficient time between the transfer operation and the end of the cycle of the single cam assembly for the completion of rotation of the type wheel, or other conditioning of the printing element and the actual printing operation. In some printing telegraph receiving apparatus having a single operating cam assembly, such for example, as that exemplified in the copending application Serial No. 77 ,793, the printing operation is timed to precede the transfer operation in each cycle of the cam assembly so that the printing operation always lags one cam cycle behind the transfer operation, and at the completion of any message, the signal combination for the last character or function remains in storage in the code disc selector mechanism and necessitates the introduction of an idle cycle of the selector cam assembly for its clearing out. In the printing telegraph receiver mechanism according to the present invention, the printing operation and also the operation of the function mechanism follows the transfer operation in the general cycle of operation of the mechanism which may be considered as beginning vth the starting of the seiector cam assembly 61 into rotation Aand terminating with the arrestment of the cam assembly |35? carried by the main or inner operating shaft. It will thus be apparent that the printer always clears out and prints in accordance with the last signal combination received and no signal combination is ever left in storage in the selector mechanism.

In the foregoing general description of the printing telegraph apparatus, in accordance with the invention, certain details were not described because the description was restricted to Fig. 1, in which details could not be clearly shown. They are, however, shown in Figs. 3 and 4, and an alternative embodiment of one feature of the invention is shown in Figs. 2 and 3. The details and alternative embodiment will now be described having reference particularly to the detailed showings.

M odz'fied type pcllet'opcrating 4mechanism Reference numeral 26| which appears in Fig. 2 designates a print hammer operating bail which is in the form of a bell crank lever and comprises arms 252 and 263. The free end of arm 262 supports a cam follower roller 264 which engages the periphery of print controlling cam 255 which may be identical with print controlling cam |54 in Fig. l and may operate in exactly the same manner and according to the same timing. IThe pivotal mounting for bail 25! (not shown) may lbe identical with pivot rod |54 of bail |53 in Fig.

1. The location of the pivotal mounting for bail 26| is indicated by the screw 261. Arm 263 of bail 26| is provided with an arcuate slot 266, the center of the arc of which coincides with the pivotal axis of bail through which extends a clamping screw 269 which threadedly engages one arm 21| of a bell crank 212. Bell crank 212 is pivoted coaxially with bail 26|, the screw 261 serving as the upper pivot for the bell crank. Arm 21| of bell crank 212 rests upon arm 263 of bail 26|, and screw 269 clamps the two arms rigidly together, the slot 268 affording provision for angular adjustment of bell crank 212 relative to bail 26|. Bell crank 212 has an arm 213 disposed in a horizontal plane considerably above that in which arm 21| is located, and specically, in the plane of the type wheel. A vertical -bar 214 integral with arm 21| and 213 interconnects the two arms and completes bell crank 212. Upper arm 213 of bell crank 212 is provided with a plurality of apertures 216, any one of which may receive one end of a tension spring 211, the other end of which is connected to a stationary bracket 218. Spring 211 biases bell crank 212 in a counterclockwise direction and thus urges cam follower roller 264 into engagement with the periphery of cam 266. Spring 211 furnishes the power for actuating the type pallets, and by shifting the foremost end of spring 211 from one to another of the holes 216, the tension of the spring may be increased or decreased as desired.

At its free end, arm 213 of bell crank 212 carries a screw 219 which supports a spring post 28|. A print hammer or type pallet operating member 282 is provided in its foremost end with an open ended slot 203 which fits over screw 210, the foremost end of print hammer 282 resting upon arm 213 of bell crank 212. Print hammer 282 is guided and further supported for reciprocational movement by a bracket 234 which may be similar to bracket |16 in Fig. l. A tension spring 286, which has one end engaging print hammer 202 and the other end engaging spring post 28|, urges print hammer 282 to extreme position of retraction, which may be determined by engagement of the closed end of slot 283 with lslot 219 or by engagement of a laterally extending projection 281 of print hammer 282 with adjustable eccentric 288 secured by screw 289 to stationary bracket 29| which supports ribbon spools 292. Print hammer 282 is provided with a shoulder 203 which may come into engagement with bushing 288, when the print hammer is reciprocated rearwardly of the printing telegraph receiving unit, to limit the operating stroke of the print hammer and prevent excessive reciprocation of the type pallets.

In Fig. 2 the prin'ting mechanism is shown in the condition which exists just before ,a printing operation, bail 26| and bell cranks 262 being in extreme clockwise position andthe free end of print hammer 282 being retracted well back from the type pallet. As cam follower roller 264 traverses the drop-01T in cam 266, bail 26| and bell crank 212 are rocked by spring 211 to extreme counterclockwise position, the movement to this position being relatively sharp. Screw 219 engages the inner or closed end of slot 283 in print hammer 282 and positively reciprocates the print hammer toward the inner end of the type pallet which is aligned therewith. Th-e positive movement of print hammer 282 by bell crank 212 ceases when cam follower roller 264 engages. the innermost portion of the periphery of cam 266 and the termination of the positive movement occurs just before the free end of print hammer 282 engages the aligned type pallet. The kinetic energy of print hammer 282 causes the print hammer to continue to move.

rearwardly of the printing unit after bell crank 212 has been arrested, the inner end of slot 233 drawing away from screw 219 and spring 286 yielding to permit the additional or overtravel movement of the print hammer. The overtravel is suflicient to drive the type pallet radially of the type wheel to eiect printing, the free end of the print hammer 282 moving into the space between the typ-e pallet on either side of the one actuated. As soon as the kinetic energy of print hammer 282 has been dissipated, spring 266 retracted the print hammer until the inner end of slot 283 engages screw 219 or until projection 281 engages bushing 288, and such retraction is sunicient to Withdraw the free end of the print hammer from between the type pallet even though the rotation of cam 266 may not have been sufficient to begin the movement of bail 26| and bell crank 212 in clockwise direction. From the foregoing, it will be observed that printing is accomplished by overtravel of the print hammer as in the embodiment of the invention previously described. In the mechanism according to Fig. 2, however, only the print hammer 232 overtravels whereas in the embodiment shown in Fig. 1, the print hammer and the bell crank to which it is articulated overtravel.

Modjed type wheel structurev Fig. 3 discloses a type wheel for the hereinbefore described printing telegraph receiving unit which may be considered as an improvement on is indicated generally by the reference numeral 30| and its foundation is a cast or turned wheel which may comprise upper and lower flanges 302 and 303, respectively, joined by integral drum portion 304. The inner surface of drum portion 304 is-cylindrical and the external surface includes a ridge 306 integral with the drum portion 304 and located midway between flanges 302 and 303. The face of ridge 306 may be flat and the sides thereof are curved toward the flanges 302 and 303, the inner faces of which also curve to meet the curving sides of ridge 306 and form therewith spaced annular grooves of semcircular .cross section. A plurality of radially directed type pallet slots are provided in the type wheelv 30|, the slots being cut entirely through the flange 303, entirely through the drum portion 304, but only partially through the thickness of flange 302.

Each of the slots in type wheel 30| receives and slidably supports the shanks 301 of two type pallets 308. The type pallet Shanks 301 extend into the interior of type wheel 30| sufciently far that they may be engaged and actuated by print hammer 282 to effect printing. The typ-e pallets 308 in the upper row have in their Shanks 301 notches 30S which open downwardly and those in the lower row have similar notches 303 which open upwardly. A garter spring 31| extends through all of the notches 303 of the type'pallets v308 in a row and biases them to their innermost positions radially of the type wheel. The annular ridge 306, which in cooperation with the inner faces of the flanges 302 and 303 denn-es peripheral grooves, separates the garter springs 3|| and maintains them in the desired positions.

When any type pall-et 308 is reciprocated outwardly radially of type wheel 30| by print hammer 232, the garter spring 3| which engages the shank of the type pallet distends slightly, thus permitting the movement of the type pallet, and thereafter restores the type pallet to innermost position.

The widths of the shanks of type pallets 303 are such that the lower of the shanks 301 of the lower row are substantially flush with the lower surface of flanges 3il3 and the type pallets .are retained in the slots in type wheel 30| by a plate 3|2 which may be secured to flange 303 by a plurality of screws 3|3 threadedly engaging sectors of flange 303 between slots therein. Plate 3|2 may have a depressed central portion 3M which carries a locating pin 3|5 and has a plurality of apertures for clamping screws. A hub 3|`| slidable upon type wheel shaft 88 supports Ithe depressed portion 3|4 of plate 3|2 and is other pair of contacts.

provided with a slot 3|8 which receives locating pin 3|6 and thereby establishes a predetermined angular position between type wheel 30| and hub 3|'|. Clamping screws 3|9 extend through the apertures in the depressed portion of plate 3|2 and threadedly engage hub 3|'| thereby clamping type wheel 30| securely to the hub.

Keyboard transmitter shunt unlatchz'ng mechemism If reference is had to copending application Serial No. 77,796 of Albert H. Reiber, description will be found therein of apparatus for performing a function which involves the closure of a pair of contacts and the opening of another pair of contacts. The contact pair which becomesA closed places a direct shunt across the keyboard transmitter contacts, so that impulses cannot be impressed upon the line if the local keyboard transmitter mechanism is operated. The other pair of contacts is included in the circuit of the start magnet of a tape transmitter if such a transmitter is to be used, so that when the contact pair is opened the start magnet of the tape transmitter will be de-energized and the transmitter will be arrested. The copending application discloses a latch for latching in operated condition the function lever which closes the rst described pair of contacts and opens the The copending application also discloses a manually operable control located at a point remote from the keyboard for unlatching the function lever. The present invention includes apparatus for unlatching the transmitting contact shunt function lever directly from the keyboard, and by means of a key lever which is normally operable for initiating the transmission of a signal` combination.

Referring now to Figs. 2 and 4 the reference numeral 32| designates contact springs which may be connected by suitable conductors so that when closed as shown in Fig. 2 they shall establish a direct shunt or a short circuit across the keyboard transmitting contacts previously described. Reference numeral 322 indicates one of a pair of normally closed contact springs which may be included in the circuit of a tape transmitter mechanism and which, when opened as shown in Fig. 4, which is intended to correspond in condition to Fig. 2, the circuit of the start magnet will be interrupted and the magnet will become de-energized to effect arrestment of the tape transmitter. The circuits form no part of the present invention and they are fully shown in copending application Serial No.

A function lever 323 pivoted at 323 is biased in clockwise direction by a tension spring 323 and normally occupies the dotted line position shown in Fig. 2. Lever 323 is provided with contact operating extensions 321 and 328, the former of which closes contact pair 32|, and the latter of which opens Contact pair 322 when lever 323 is rocked to extreme counterclockwlse position which position is indicated in full line in Fig. 2. The rocking of lever 323 to ext-reine counterclockwise position is accomplished by one of the previously identified function bars |03. Function lever 323 is provided with a latching lug 329 which, when the particular function bar |93 has been rocked in clockwise direction during the hereinbefore described operation of testing for functions, falls in against the left-hand side of the function bar |93 and holds it from returning to extreme counterclockwise position at the end of the function testing operation. Thereafter upon the rearward reciprocation of function bars |93, the particular one shown in Fig. 2 which has become latched by projection 329, rocks lever 323 to the position shown in full lines, thus effecting the closure of contact springs 32| and the separation of contact spring 322.

A bracket 33| secured to secondary casting member 64 pivotally supports a latch lever 332 which is biased in counterclockwise direction by tension spring 333. At right-hand end as viewed in Fig. 4, lever 332 is step-cut to provide a shoulder for engaging lever 323 near its right-hand end, as viewed in Fig. 2, and blocking the return of lever 323 to normal or extreme clockwise position. When lever 323 occupies the normal or dotted line position as shown in Fig. 2, the latching shoulder of lever 332 underlies a portion of lever 323.

At its left-h-and end as viewed in Fig. 4 the lever 332 has a portion 334 sloping obliquely downwardly. In the initial portion of the description of Fig. 1, the key levers of the keyboard transmitter mechanism were indicated generally by the reference numeral 2|. A particular key lever which initiates the generation cf a signal combination that will be hereinafter specifically identified is indicated in Fig. 4 by reference numeral 336. Key lever 336 has secured thereto adjacent to the point at which it is pivotally mounted, a clamp 331 which includes reverted fingers 338 fitted over one edge of the key lever,

and clamping screw 339 engaging the other edge of the key lever and drawing reverted ngers 338 firmly into engagement with the first mentioned edge. Clamp 331 has secured thereto or integral therewith, an arni 34| which extends rearwardly of the keyboard transmitter mechanism (rightwardly as viewed in Fig. 4) and arm 34| has a vertically directed portion 342 which emerges from keyboard base casting I8 through an aperture at the rear thereof and terminates just under lever 332 adjacent to the downwardly sloping portion 334 thereof.

In the normal condition of the transmitter shunt function mechanism, function lever 323 is in ex-treme clockwise position and latching lever 332 is also in extreme clockwise position with its latching shoulder underlying function lever 323 by which lever 332 is held in extreme clockwise position in opposition to tension spring' 333. When lever 332 is in this position, its left-hand end as viewed in Fig. 4 is held elevated above the upper end of arm 342 of clamp 331 a sufficient distance that arm 342 will not come into engagement with any portion of lever 332 upon being rocked in counterclockwise direction by the depression of key lever 336. Thus, latching lever 332 places no drag upon key lever 336 when function lever 323 is in unlatched condition and the touch of key lever 336 is entirely normal.

When the printing telegraph receiving unitV responds to the signal combination which is as signed to the operation of function lever 323, thelever is rocked in countercloekwise direction and in being so rocked, it clears the latching shoulder of lever 332 whereupon spring 333 rocks lever 332 in counterclockwise direction to interpose the latching shoulder into the restorational path of lever 323 and the left-hand end of lever 332 as viewed in Fig. 4 rocks downwardly into a position of substantial engagement with the upper end of arm 342 of clamp 337, as shown in Fig. 4.

When it is desired to unlatch function lever 323, key lever 336 is depressed. This causes arm 342 of clamp 331 to be rocked in counterclockwise direction whereby downwardly sloping portion 334 of lever 332 is cammed upwardly. Lever 332 is thus rocked in clockwise direction suficiently to disengage the shoulder alt the righthand end thereof from function lever 323, which is restored to eXtreme clockwise position against xed stop 343 by tension spring 326, thereby moving into position to overlie the right-hand end of lever 332 and hold it depressed, whereby the left-hand end, which has the downwardly sloping portion, is held elevated.

Although the clamp 331 may be secured to any of the key levers 2 I, it has been found particularly satisfactory to secure it to the key lever which initiates the generation of the unshift or letters signal combination, identified herein as 336. According to a widely used system of printing telegraph signal transmission, each signal combination representing a character or a function consists of a permutation code combination of marking and spacing impulses preceded by a start impulse and followed by a stop impulse. It is frequently the custom to represent a marking impulse by a closed line condition, in which case current flo-ws, and a spacing impulse by an open line condition in which case no current iiows. It is also the custom to employ a spacing condition for .fthe star-t impulse and a marking condition for the stop impulse. In the rest condition of the transmitting apparatus, a pair of contacts that are identiiied with the stop impulse are closed and remain closed. When the transmitter is set in operation, these contacts are opened, thereby creating a spacing condition of the line which is the start impulse. The impulses for the particular signal combination are then generated successively, and after the last code impulse has been generated, the stop impulse contacts are permitted to be closed whereby the stop impulse is impressed upon the line. The start impulse of spacing nature sets in operation the receiving selector mechanism of a printing telegraph receiving unit connected to the line and the stop impulse of marking nature arrests the receiving selector mechanism. It is also customary to permit successive marking impulses to overlap, so that two or more successive marking impulses establish on the line a single prolonged period of marking condition.

It will be apparent that when contact springs 32! are closed and function lever 323 is latched,

a closed line condition duplicating the rest condition of the stop impulse contacts will be connected in shunt across the stop impulse contacts so that even if the transmitting distributor should be released for operation no start impuls-e of spacing nature will be applied to the line due to the opening of the stop impulse contacts. When key lever 333 is operated, it will release the transmitting distributor sleeve 3l for a cycle of operation. Arm 342 m-ay be arranged to be moderately slow in tripping latch 332 so that the transmitting cam assembly shall have rotated beyond the angle during which the start impulse is generated and shall be attempting to impress upon the line .the code impulses. Until the contact springs 32H shall have become separated, these code impulses will not actually be applied to the line, but after the separation of the contact springs the line will be under the control of the .transmitting distributor cam assembly. According to a previously mentioned commonly used permutation code system of printing telegraph signal transmission, the all marking combination is assigned to the unshift or letters function. In

this signal combination the spacing condition of the start impulse is followed by a succession of marking impulses which overlap and the last of which overlaps the beginning of the stop impulse so that the line is continuously closed following the start impulse. Arm 342 of clamp 337 carried by key lever 336 may be permitted to trip off latch lever 332 at any time during the transmission of the code impulses of the letters or unshift signal and the line will not be thereby affected, because the line will continue to be closed following the opening of contact springs 32H throughout the transmission of the remainder of the code impulses and including the stop impulse. The receiving' mechanism of any printing telegraph unit connected, to the line will thus be maintained in rest or stop condition and there will be no manifestation of the opening of contact springs 32E nor of the rotation o-f the transmitting distributor in response to operation of the letters key lever 333.

Should the tripping of latch 332 be assigned to any other key lever than the letters key lever, the signal combination generated by operation of that key lever will include at least one spacing impulse. Such impulse may result in the transmission of a jumb-led signal combination for the reason that if latch 332 is tripped oif so as to permit opening of Contact springs 32l after the start impulse interval of the transmitting distributor cycle but before the generation of the spacing impulse in the code combination the receiving selector mechanisms of printing telegraph receiving units connected to the line will be set in operation in response to the spacing impulse in the code combination and not in response to the start impulse preceding the code combination, and will operate after the transmitting distributor has come to rest thus interpreting the stop impulse as one or more marking impulses of a, vcode combination. The result will be the printing of an undesired character or the performance of an undesired function. It will be observed from the foregoing that the letters or unshift key lever is particularly Well adapted to arrangement, and substitution of parts and elements without departing from the spirit of the invention and Within the scope of the appended claims.

What is claimed is:

1. In a printing telegraph apparatus, a keyboard transmitter mechanism including a plurality of key levers, a receiving `apparatus including a function lever, means for actuating said function lever, means for latching said function lever in actuated condition, and means associated With one of said key levers f-or releasing said latching mechanism.

2. In a printing telegraph apparatus, a key- Aboard transmitter mechanism including a -plurality of key levers, a receiving apparatus including a function lever, means for yactuating said function lever, means for latching said function lever in actuated condition, and means engageable by one of said key levers only When said function lever is in latched condition for releasing said latching means.

3. In a printing telegraph apparatus, a keyboard transmitter mechanism including a plurality Yof key levers and a plurality of transmitting contacts controlled by said key levers, a receiving apparatus including a function lever, means for actuating said function lever, means operated 'by said function lever for short circuiting said transmitting contacts, means for latching said function lever in actuated condition, and means associated with a `predetermined one of said key levers which controls the transmitting contacts to generate a signal combination the code impulses of Which maintain a line condition identical with that afforded by the contact short-circuiting means for releasing said latching means.

4. In a printing telegraph apparatus, a keyboard transmitter mechanism including a plurality of key levers and a plurality of transmitting contacts controlled by said key levers, a receiving apparatus including a function lever, means for actuating said function lever, means controlled by said function lever for short circuiting said transmitting contacts, means for latching said function lever in actuated condition, and means carried .by a predetermined one of said key levers which controls the transmitting contacts to generate a signal combination non-e of the code impulses of which will set in operation said receiving apparatus for disabling said latching means.

5. In a printing telegraph apparatus, a telegraph line, a keyboard transmitter mechanism connected to said line including a plurality of key levers and a yplurality of transmitting contacts operable under the control of said key levers to apply to said line marking or spacing signal conditions, a receiving apparatus including a function lever, means for actuating said function lever, means controlled by said function lever for establishing a marking signal condition Which blanke-ts and renders ineffective said transmitting contacts, means for latching said function lever in actuated condition, and means associated with a predetermined one of said key levers which controls the operation of the transmitting contacts to apply to said line a signal combination all of the code impulses of which are of marking signal nature for disabling said latching means.

6. In a printing telegraph apparatus, a signal transmitting mechanism, a plurality of key levers for individually controlling said signal transmitting mechanism, a receiving apparatus, and a mechanical device in said receiving apparatus operable thereby into engagement With one of said key levers and restorable -by said one key lever to unoperated condition out of engagement With said one key lever.

7. In a printing telegraph apparatus, a signal transmitting mechanism, a plurality of key levers flor individually controlling said signal transmitting mechanism, a signal receiving apparatus, a mechanical device in said receiving apparatus operable thereby, and latching means for said mechanical device movable into engagement with one of said key levers and restorable by said one key lever to unlatching condition out of engagement with said one key lever.

8. In a printing telegraph apparatus, a signal transmitting mechanism, a plurality of key levers for individually controlling said signal transmitting mechanism, a signal receiving apparatus, a mechanical device in said receiving apparatus yoperable thereby, and latching means for said mechanical device normally out of engagement with any key -lever and movable into engagement with one of said key levers upon latching said mechanical device and restorable by said one key lever 'to unlatching condition out of engagement with said one key lever.

9. In a printing telegraph apparatus, a signal transmitting mechanism, a plurality of key levers for individually controlling said signal transmitting mechanism, a signal receiving apparatus, a mechanical device in said receiving apparatus op erable thereby, means for latching said mechanical device in operated condition, and means carried by one of said key levers into engagement with which said latching means moves upon latching said mechanical device for disabling said latching means.

CARL A. LEVIN. 

